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在不同的干旱条件下,VPD和SWC对生态系统碳水合的不同影响
Chen Zheng1, Shaoqiang Wang2, Jinghua Chen1
1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
The Science of the total environment
|September 22, 2023
概括
生态系统的用水效率 (WUE) 根据生态系统的干旱情况对干旱的反应不同. 在潮湿的地区,增加的蒸汽压力赤字 (VPD) 降低了WUE,而在干旱地区,较低的土壤含水量 (SWC) 增加了WUE.
科学领域:
- 生态生态学 生态生态学
- 环境科学 环境科学
- 气候科学 气候科学
背景情况:
- 生态系统用水效率 (WUE) 量化碳-水相互作用,定义为总初级生产率 (GPP) 与蒸发转化率 (ET) 的比率.
- 了解WUE对干旱的反应至关重要,但其在不同生态系统干旱的行为以及GPP和ET的具体作用仍然不清楚.
研究的目的:
- 研究生态系统WUE,GPP和ET如何在不同的生态系统干旱条件下对大气 (蒸汽压力赤字,VPD) 和土壤干旱 (土壤含水量,SWC) 作出反应.
- 确定GPP和ET在干旱压力下对WUE变化的相对贡献.
主要方法:
- 利用来自26个全球流量塔站点的数据.
- 雇员包装和随机森林模型分析每日WUE,GPP和ET对VPD和SWC的敏感性.
- 基于干燥度指数 (DI =潜在的蒸发透气/降雨) 的生态系统.
主要成果:
- 在潮湿 (DI < 1) 的生态系统中,WUE对VPD的敏感性是负的,在干旱 (DI > 2) 的生态系统中,WUE对SWC的敏感性是正的.
- 在潮湿地区,GPP对VPD诱导的WUE变异性有63%的贡献;在干旱地区,ET对SWC诱导的WUE变异性有68%的贡献 (SWC <第60个百分点).
- 在特定条件下,VPD对WUE的影响比SWC更大 (VPD<90百分位或SWC>50百分位).
结论:
- 生态系统的干燥是影响WUE对VPD和SWC反应的关键因素.
- 不同的机制驱动WUE变化:降低GPP影响湿WUE,而降低ET影响干WUE在低SWC下.
- 这些发现强调了需要将生态系统干旱纳入碳水合模型的必要性.
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